Extended Efficient Usage of Emergency Services Keys

ABSTRACT

An emergency services key (e.g., ESQK or ESRK) is guaranteed to be available from a limited size ESQK pool. A plurality of ESQKs are grouped into a pool of emergency service keys “ESQK Pool ID”, each including anywhere from 1 to N number of ESQKs. Each ESQK preferably has a “Timestamp”, information relating to the specific emergency E911 call (“Call Data ID”), a guard timer, and an optional hold timer. The ESQK having a Call Data ID=“NULL”, and having the oldest Timestamp, is chosen for selection. If no such ESQK has both Call Data ID=NULL and the oldest Timestamp is found, then the ESQK with merely the oldest Timestamp is selected. The timestamp is reset to a current time plus a guard timer, or hold timer if desired.

This application is a Continuation-In-Part of U.S. application Ser. No.11/797,445, filed May 3, 2007, which claims priority from U.S.Provisional Application No. 60/797,359, filed May 4, 2006, the entiretyof both of which are expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to long distance carriers, InternetService Providers (ISPs), and information content deliveryservices/providers and long distance carriers. More particularly, itrelates to emergency call systems (e.g., E9-1-1) including wireless andInternet Protocol (IP) based Voice Over Internet Protocol (VoIP)emergency call systems.

2. Background of Related Art

9-1-1 is a phone number widely recognized in North America as anemergency phone number that is used to contact emergency dispatchpersonnel. Enhanced 9-1-1 (E9-1-1) is defined by an emergency call beingselectively routed to an appropriate PSAP, based on a special identifier(P-ANI, or “Pseudo Automatic Number Identifier”, also referred to as“ESxK”), and includes the transmission of callback number and locationinformation when 9-1-1 is used. E9-1-1 may be implemented for landline,cellular or VoIP networks. Regardless of the network type, a 9-1-1service becomes E-9-1-1 when automatic number identification andautomatic location information related to the call is provided to the9-1-1 operator at the PSAP.

A Public Service Answering Point (PSAP) is a dispatch office thatreceives 9-1-1 calls from the public. A PSAP may be a local, fire orpolice department, an ambulance service or a regional office coveringall services. As used herein, the term “PSAP” refers to either a publicsafety access point (PSAP), or to an Emergency Call Center (ECC), a VoIPterm.

FIG. 4 shows a conventional landline public safety access point (PSAP)to automatic location identifier (ALI) connection.

In particular, FIG. 4 shows a PSAP 400 connected to one AutomaticLocation Identifier (ALI) database 401. An ALI is a database thataccepts a PSAP query with telephone number, relates the telephone numberto an address and provides that address (location information) back tothe PSAP in a manner that works for the customer premise equipment (CPE)display. An ALI is typically owned by a LEC or a PSAP, and may beregional (i.e. connected to many PSAPs) or standalone (i.e. connected toonly one PSAP). There is no one single standard interface protocol forPSAP-ALI connection/communication.

Upon receiving a 9-1-1 call, the PSAP 400 queries the ALI 401 forlocation data. The ALI database 401 accepts the query from the PSAP 400for location. The query includes the telephone number of an emergencycaller. The ALI database 401 relates the received telephone number to aphysical street address and provides that street address (locationinformation) back to the PSAP 400 in a manner that works for thecustomer premise equipment (CPE) display at the PSAP 400.

FIG. 5 shows a context diagram for a conventional non-landlinepositioning center (e.g., an Internet based voice over Internet Protocol(VoIP) positioning center).

In particular, the ALI database 401 includes a conventional emergencyservices key (ESQK or ESRK) in a location request sent to an appropriatepositioning center 402 (XPC). The emergency services key (ESQK or ESRK)is used by the positioning center 402 as a key to look up the locationand other call information associated with the emergency call.

In non-landline telephony, the PSAPs 400 query the ALI 401 for locationinformation. However, the ALI 401 is not pre-provisioned with locationdata for non-landline calls (e.g. cellular, VoIP etc) and mustcommunicate with other network entities to obtain and deliver locationdata to the PSAP 400.

Non-landline telephony standards (e.g. cellular, VoIP etc) have mandatedthat ALIs 401 maintain connectivity to a positioning center 402 that isable to provide current location data for a non-landline call. In thecurrent state of technology, the positioning center 402 provides thecaller's location and the callback number to the ALI, which passes it tothe requesting PSAP. As can be seen in FIG. 5, an ALI may maintainconnectivity to more than one positioning center via multiple interfacetypes—both standard and non-standard (e.g. NENA-02, E2/E2+/V−E2(ESP),PAM, etc.).

Whether landline or non-landline, conventional emergency call centers,e.g., public safety access points (PSAPs) 400, use emergency serviceskeys such as an emergency services query key (ESQK) or an emergencyservices routing key (ESRK), collectively referred to herein as ESxK, toquery for location information. An emergency services key identifies anemergency call, and is associated with a particular selective router 417associated with a given public safety access point (PSAP) 400. Theemergency services keys ESQK and ESRK are conventionally used to querythe automatic location identification (ALI) database 401 for thelocation of a given emergency caller. An emergency services key isdelivered to the E9-1-1 selective router 417 and is the callingnumber/ANI for the call to the PSAP 400. The emergency services key isused by a selective router 417 as a key to selective routing dataassociated with the emergency call. The emergency services key isdelivered by the selective router 417 to a PSAP 400 as the callingnumber/ANI for the emergency call, and is subsequently used by the PSAP400 to request automatic location information (ALI) informationindicating the location of the device making the emergency call.Conventional emergency services keys conform to ten-digit North AmericanNumbering Plan Number definitions.

Existing, standardized solutions prescribe a finite pool of emergencyservices keys (ESQK and ESRK) which are allocated individually, oneassociated for each emergency call in progress. ESxK numbers are used torequest updated location information from the ALI 401 while an emergencycall is active, and as such, as appreciated by the inventors hereof, aresubject to number exhaustion if the number of active emergency callsexceeds the number of ESxKs in the pool. But because ESxKs (ESQKs andESRKs) are dynamically assigned at the time of call origination, andbecause the pool of ESxKs is limited, the inventors appreciate that itis possible for the pool of available ESxKs to run out.

For systems which implement ESQK and/or ESRK keys, it is a well knowntechnique to use timers and default ESxKs to avoid problems associatedwith a limited pool of ESxKs. Timers have been specified and implementedto limit the amount of time that an ESxK can remain allocated to anemergency call, without regard for the actual call duration. Forexample, if a call continues after the timer has expired; the specificESxK which was used to obtain updated location information can getreassigned to a new incoming emergency call.

However, timers are based solely on estimated call duration, a valuewhich could be exceeded. Since emergency calls are numerous, and canremain active for long periods of time once initiated, some serviceproviders have increased the number of allocated ESxK pools in an effortto minimize number pool exhaustion. Additionally, reliance on timersrequires much larger pools of ESxKs to be allocated, which is aninefficient use of numbers, and may potentially lead to numberexhaustion.

The conventional technique of using timers to expire the ESQK and ESRKallocation could prove to be devastating if a given emergency call usingthat expiring ESxK is still active. This is especially true if there isupdated location information which would help provide emergencyassistance to the caller.

Moreover, ESxK numbers must be purchased, so large numbers of ESxKsrepresent a direct cost to a provider. Also, as requirements forcapacity increase, existing systems must often increase the size of theESQK and ESRK number pool that they purchase, leading to additionalcosts for ESQK and ESRK number purchases, additional costs to implement,and additional costs to maintain these larger number pool sizes.

Thus, emergency services keys, e.g., the emergency services query key(ESQK) or the emergency services routing key (ESRK), identify a callinstance at a VoIP positioning center (VPC). The ESQK is selected from apre-provisioned pool by the VPC and delivered to the PSAP (Public SafetyAnswering Point) as the calling number for an emergency call. The ESQKis subsequently used by the PSAP to request ALI (Automatic LocationIdentification) information for the call from the VPC. The ESQK is usedby the VPC as a key to look up the location object and other callinformation associated with the emergency call instance. Thisinformation is returned to the PSAP.

But, the size of an ESQK pool is limited for VoIP emergency calls.During normal operation emergency calls are associated with an ESQK aslong as the emergency call is in process. As soon as the call isterminated, the ESQK is “released” and marked as free. Once allpre-provisioned ESQKs have been associated with emergency calls they aremarked as “unavailable/in-use.” New incoming emergency calls coming inat that time must still be served and assigned an ESQK from the givenpre-provisioned pool.

Currently systems conform to NENA VoIP Architecture For Enhanced 9-1-1Services, NENA standard 08-001. However, such systems are complicated innature, and thus not practical.

There is a need for a more efficient use of available emergency serviceskeys.

SUMMARY OF THE INVENTION

In accordance with the principles of the present invention, a method andapparatus for recyclably using an emergency services key selected fromamong a limited size pool comprises selecting an emergency services keyfrom a limited size pool having an older timestamp associated therewithfrom among those in the pool, in the event that no emergency serviceskey in the pool meets the first attempt selecting criteria. A timestampassociated with the selected emergency services key is reset to acurrent time plus a value of a guard timer. In this way, selection ofthe emergency services key is assured to be available when selected.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become apparent tothose skilled in the art from the following description with referenceto the drawings:

FIG. 1 a shows an exemplary ESQK data store, in accordance with theprinciples of the present invention.

FIG. 1 b shows an exemplary ESQK Pool ID data store, in accordance withthe principles of the present invention.

FIG. 2 a shows exemplary contents of the ESQK data store shown in FIG. 1a, in more detail, in accordance with the principles of the presentinvention.

FIG. 2 b shows exemplary contents of the ESQK Pool ID data store shownin FIG. 1 b, in more detail, in accordance with the principles of thepresent invention.

FIG. 3 illustrates exemplary selection of an emergency services key(e.g., an emergency services query key (ESQK)) from a pool of ESQK keys,in accordance with the principles of the present invention.

FIG. 4 shows a conventional landline public safety access point (PSAP)to automatic location identifier (ALI) connection.

FIG. 5 shows a context diagram for a conventional non-landlinepositioning center (e.g., an Internet based voice over Internet Protocol(VoIP) positioning center).

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present invention provides for the management of a limited sizeemergency services key pool (e.g., an ESQK pool) in such a way as toensure that an ESQK can always be handed out to an incoming emergencycall, even if all ESQK pool members are marked as unavailable and tohold onto it even after the call is released. The invention appliesequally to efficient use of emergency services routing keys (ESRKs) usedin the wireless industry where the gateway mobile location centre (GMLC)takes the functional role of the voice over Internet Protocol (VoIP)positioning center (VPC). Ultimately the invention applies to anylimited size pool of unique numbers that need to be dynamicallyallocated to a resource for a limited time in such a way to alwaysguarantee the availability of a pool element.

Selecting an ESQK from a Pool:

FIG. 1 a shows an exemplary ESQK data store 200, in accordance with theprinciples of the present invention.

In particular, as shown in FIG. 1 a, a plurality of ESQKs are groupedinto a pool of emergency service keys, identified herein with an “ESQKPool ID” 201.

The ESQK pool ID includes ESQK(s) 202. The ESQKs 202 element of the ESQKdata store 200 is capable of containing anywhere from 1 to N number ofESQKs 202, N being any number greater than 1.

The size of N is limited by network factors, such as the size of adatabase, but mostly based on the number of ESQKs assigned for use bythe given network element.

Each ESQK 202 preferably has a “Timestamp” 203 associated therewith. Thetimestamp 203 preferably relates to a representation of the current timeof day of assignment of the associated ESQK 202 to a specific emergency(e.g., E911) call.

Each ESQK 202 also includes information relating to the specificemergency E911 call, referred to herein as “Call Data ID” 204. The CallData ID 204 information identifies the specific emergency E911 call.

FIG. 1 b shows an exemplary ESQK Pool ID data store 250, in accordancewith the principles of the present invention.

The ESQK Pool ID data store 250 is a table associating an ESQK pool ID201 with a possible Guard Timer 252 and Hold Timer 253.

FIG. 2 a shows exemplary contents of the ESQK data store 200 shown inFIG. 1 a, in more detail, in accordance with the principles of thepresent invention.

In particular, as shown in FIG. 2 a, an exemplary ESQK Data Store 200includes three (3) ESQK pools: ESQK pool #1 (as depicted in rows 301 and302, ESQK pool #2 (as depicted in rows 303 and 304) and ESQK pool #3 (asdepicted in rows 305 and 306). In this exemplary embodiment, each of theexemplary ESQK pools #1 (301, 302) and #2 (303, 304) contain two ESQKs202, and the exemplary ESQK pool #3 (305, 306) contains one ESQK 202.

FIG. 2 b shows exemplary contents of the ESQK Pool ID data store 250shown in FIG. 1 b, in more detail, in accordance with the principles ofthe present invention.

In particular, as shown in FIG. 2 b, ESQK pools #1 307 and #2 308 eachhave a Guard Timer 252 associated therewith, but no Hold Timer 253,whereas pool #3 309 contains both a Guard Timer 252 and a Hold Timer253—in this example a Hold Timer 253 of 2 hours.

FIG. 3 illustrates an exemplary selection of an emergency services key(e.g., an emergency services query key (ESQK)) from a pool of ESQK keys,in accordance with the principles of the present invention.

In particular, as shown in FIG. 3, an ESQK 202 is picked as follows fora given ESQK pool.

In step 100 of FIG. 3, the ESQK 202 in the ESQK pool having a Call DataID 204 equal to “NULL” (NULL is used as a synonym for “not set” in thiscontext), and having the oldest Timestamp 203, is chosen for selection.In decision step 102, if no such ESQK having both Call Data ID=NULL andthe older Timestamp is found in the given ESQK pool 200, then the methodmoves to step 104 where the ESQK with merely an older or oldestTimestamp is selected.

The inherent logic is that in the latter scenario ESQKs that are nolonger associated with active emergency calls might be incorrectlymarked to still be in use. The present inventors realized that thislogic is no longer true under extreme conditions, such as an ESQK poolsized too small, or extremely high call volume, typically generated in alab stress test environment. For most practical purposes the likelihoodof this happening is extremely low. In this way, the inventive methodalways guarantees successful selection of an ESQK as long as the numberof ESQKs in a given pool is >=1.

In step 106, the Timestamp 203 and Call Data ID 204 are preferablyupdated. The ESQK's timestamp 203 is set to the current time plus thevalue of the Guard Timer 252.

Returning an ESQK to a Pool:

When an emergency call is terminated the ESQK 202 that has beenassociated with the call up to that point is released. To achieve this,the ESQK record is retrieved from the ESQK data store 200, and the CallData ID 204 parameter for that particular ESQK record is set to NULL.

In the call termination process the ESQK Pool ID Data Store 250 ischecked. If no Hold Timer 253 is defined, then the Timestamp 203parameter for that ESQK record is left unchanged. In this way, the ESQKrecord that was used retains the Timestamp 203 of the last time it wasselected plus the value of the GuardTimer 252. At the time of the calltermination this TimeStamp 203 may be in the future, in which case theESQK 202 associated with this record will be further protected for thespecified duration. However, if a Hold Timer 253 is defined, theTimestamp 203 parameter for that ESQK record is updated to the currenttime plus the value of the Hold Timer 253.

In this way an emergency services key such as an ESQK can be protectedfor a well specified duration after a termination event. This is a keyto the present invention and crucial from the viewpoint of the PSAP,which may want to query the data associated with a particular emergencycall well after it has been released.

As an example use of the inventive method, a request for an ESQK fromESQK pool #1 shown earlier in FIG. 2 would follow the method describedand shown with respect to FIG. 3. In the given example, ESQK“11111111111” (row 301) would be chosen since it has a Call DataID=NULL, and the oldest Timestamp.

A request for an ESQK from ESQK pool #2 would also follow the methoddescribed and shown with respect to FIG. 3. All ESQKs in ESQK pool #2 asdepicted still have a value assigned as a Call Data ID. For instance,the ESQK in row 303 has a Call Data ID=1234, and the ESQK in row 304 hasa Call Data ID=5678. Because the values for these Call Data ID is NOTNULL, they are both considered to be marked as “in-use” as referred toherein.

In this particular example, ESQK “33333333333” (row 303) would be chosensince no ESQK in the ESQK pool (i.e., ESQK pool #2) has a Call DataID=NULL, and that ESQK (i.e., ESQK “3333333333” (row 303) is the ESQK inthat ESQK pool having the oldest Timestamp. In this example, the oldestTimestamp is “Two days ago @ 8:00 AM”.

The ESQKs in pool #3 309 have a well defined Hold Timer 253, unlike theESQKs in pool #1 307 and #2 308 which have no Hold Timer 253 defined. Arequest for an ESQK from ESQK pool #3 309 would also follow the methoddescribed and shown with respect to FIG. 3. All ESQKs in ESQK pool #3309 as depicted have no value assigned as a Call Data ID 204, however,the row in 305 is still protected by the Hold Timer 253 (seen in pool #3309) and considered to be in-use. The ESQK in row 306 will be chosen.The latter ESQK was also protected by the Guard Timer 252/Hold timer 253from pool #3 309, however the Timestamp 203 indicates that the timeralready expired.

While the Timestamp 203 is represented as “Two days ago @ 8:00 AM”, itis entirely within the principles of the present invention that otherrepresentations for a Timestamp 203 are possible. For instance, theTimestamp 203 may be represented in YYYY/MM/DD/HH/MM/SS format, orequivalent, as an example.

Accordingly, the invention guarantees that for a limited size ESQK pool,an ESQK can always be selected and associated with an ongoing emergencycall with no measurable impact to existing calls.

While the disclosed examples relate to the selection of an emergencyservices query key (ESQK), the present invention is equally applicableto the selection of an emergency services routing key (ESRK).

While the invention has been described with reference to the exemplaryembodiments thereof, those skilled in the art will be able to makevarious modifications to the described embodiments of the inventionwithout departing from the true spirit and scope of the invention.

1. A method of recyclably using an emergency services key selected fromamong a limited size pool, comprising: selecting an emergency serviceskey from a limited size pool having an older timestamp associatedtherewith from among those in said pool, in the event that no emergencyservices key in said pool meets said first attempt selecting criteria;and resetting a timestamp associated with said selected emergencyservices key to a current time plus a value of a guard timer; wherebyselection of said emergency services key is assured to be available whenselected. 2-10. (canceled)